Alkylation of hydrocarbons



June 1, 1965 M. F. NATHAN ALKYLATION oF HYDRooARBoNs 4 Sheets-Sheet l Filed June 5, 1959 ini w ml

OwwmmmEOU INVENTOR. MARWN F. NATHAN BY wwv W ATToREY AGJQT June l, 1965 M. F. NATHAN 3,187,066l

ALKYLATION 0F HYDRocARBoNs Filed June 3, 1959 4 Sheets-Sheet 2 COMPRESSOR Isl NEUTRALIZATION h- PARAFFIN ALK LATE SPENT cAFTE-IT CATALYST INVENTOR. MARVIN F. NATHAN BY f1/ww ATTORNEY ISOFARAFFIN June l, 1965 M. F. NATHAN ALKYLATION OF HYDROCARBONS Filed June 5, 1959 4 Sheets-Sheet 5 INVENTUR. MARVIN F. NATHAN June 1, 1965 M. F. NATHAN ALKYLATION OF HYDROCARBONS Filed June 5, 1959 4 Sheets- Sheet 4 OmmmmaEOU United States Patent() 3,l87,966 ALKYLATN l? HYDRCARBQNS Marvin E'. Nathan, New York, NSY., assigner to Pullman Incorporated, a corporation of Delaware Filed .lune 3, 1959, Ser. No. 817,78 Claims. (Cl. 2nd- 683.612)

This invention relates to an improved condensation process and more particularly to the alliylation of isoparatlins with olens in the presence of an alkylation catalyst to produce hydrocarbon compounds boiling in the gasoline boiling range. In one aspect the invention relates to improving the etliciency and economy of an alkylation process and process conditions.

Among the various catalytic processes which have made possible and economical the production of fuels having a quality rating of better than 90 octane for both automotive and aviation use, the alkylation of isoparaihns has been foremost in importance. Some reasons for this are: isoparallins as well as olefins are converted, resulting in an increased product yield; the alkylate is essentially free from gum forming materials so that additives are not required; the alkylate has a higher tetraethyl lead response than polymerized oleiins and the performance in supercharged engines is superior to most other catalyticaliy produced fuels.

Generally, the allryiation process involves contacting an isoparafn with an olefin in the presence of a catalyst in an alkylation zone, removing the crude alkylate product and treating it either by a washing, extraction or absorbing process, to remove polymers and sulfur-bearing materials such as sulfate esters formed in the reaction zone. The treated alkylate is then deisoparaiiinized in a distillation tower and the isoparaflin removed overhead is usually recycled to the reaction zone while the alkylate is removed and treated for further purication and separation.

Many chemical and engineering problems are involved in the design and operation of an eiiicient alkylation process. The reaction between the isoparaiiin and olelin in the presence of an alkylation catalyst is exothermic and the heat of reaction must be removed during the reaction for maintenance of operating conditions. The reaction products and diluents in the feed must be removed from the hydrocarbon and catalyst phase to avoid the accumulation and interference in the isobutane-olen reaction. Unreacted constituents must be eiiiciently and economically separated from the reaction effluent or allrylate for return to the reaction zone after the desired conversion is accomplished.

, It has been known that the quality ot alkylate products is etlected by the isoparatiin concentration present in the allrylation zone during the reaction. However, a large part of the isoparan available for use in the alkylation reaction is supplied from the -deisoparainization of alkylate in the distillation zone after leaving the reactor and the quantity available for recycle in prior art operations, has been limited by the size of the distillation tower. Deisoparaiinization of prior processes represents a major cost from the standpoint of both investment of utilities and alkylation units, therefore, the amount of isoparailin recycle in conventional systems is limited by economic considerations. Furthermore, in such conventional or prior art systems, much expensive and intricate heat exchange equipment is employed between the alkylation zone and the distillation tower to attain the temperatures and pressures at which deisoparaiiinization is accomplished; for example, a typical tower bottom temperature is about 200 F. while the pressure is about ll() p.s.i.g. These temperatures and pressures are far in excess of those required for the allsylation reaction, which is usually carried out at a temperature below 80 F. under about 50 psig. These extreme temperature and pressure dif- ICC ferences between the two adjacent zones contributes to the operational expense and detracts from the eiciency of the present day processes.

In addition to these difficulties, tremendous quantities of alkylation eiiluent require intricate and costly equipment for the removal of acid and acid esters which are formed along with the alkylate product in the alkylation zone and which degrade the alkylate. To accommodate the large volume of alkylation eiiluent for the removal of sulfur-bearing materials, it has been necessary to provide oversized washing equipment to accomplish the desired result. The necessity of removing these contaminants prior to distillation is dictated by the fact that the esters decompose at the temperatures and pressures at which deisoparatlinization is accomplished and their presence in the distillation zone results in clogging the reboiler and trays of the deisoparaliinizer. For this reason, much expense is added to the overall cost of the operation.

lt is, therefore, an object of this invention to provide an improved process for the alkylation of hydrocarbons in the presence of an allrylation catalyst.

lt is another object of this invention to reduce the volurne of material for treatment in the removal of sulfurbearing materials.

lt is another object of this invention to reduce the number of treating steps to which alkylate is subjected for concentration and reinement.

Still another object of this invention is to increase thermodynamic efficiency in an alkylation process.

It is another object of this invention to provide a more e-iiicient and economical method of deisoparaiiinizing alkylate.

Still another object of this invention is to increase the ratio of isoparaihn to olelin in the reaction zone.

Still another object of this invention is to decrease lthe volume of inerts in the alkyla'tion feed.

yOther objects and advantages of the present invention will become apparent to those .skilled in the art from the following description and disclosure.

According to the preferred process of this invention, an isoparatiin is contacted with an olefin in the presence of a catalyst in an alkylat-on contactor or reactor to produce a vaporous eiiluent containing low boiling hydrocarbons, for example, parailins, and a liquid eiiluent containing catalyst, `alkylate and unreacted feed material. The catalyst is separated from .the hydrocarbon liquid eilluent and at least a portion of the hydrocarbon liquid is passed rto a distillation Zone where it is deisoparalinized. The vaporous eiiluent, which is formed by the evaporation of reactant and lower boiling hydrocarbons in the exothermie alkylation reaction and which thus provides temperature control in the present process, is removed as auto-refrigerant from the alkylation zone, Compressed and passed in indirect heat exchange With the liquid hydrocarbons in the deisopanaiiinization Zone to provide heat -thereto and to maintain distillation conditions therein. The compressed vapor or auto-refrigerant, which comprises the heat exchange medium serving to reboil the liquid hydrocarbons undergoing deisoparainization, is at least partially condensed and the condensed portion recycled to the alkylation Zone at a temperature and pressure suitable for the alkylation reaction. A vaporous overhead fraction of isoparain from the distillation zone is removed, compressed, condensed tand also returned to the alkylation zone under suitable temperature and pressure conditions,

One of the preferred embodiments of the present invention involves operating the distillation tower as a stripper, that is, Without any reflux tothe tower, or with a relatively small amount of reliux. AAnother preferred embodiment is realized by subjecting deisoparaftinized alkylate to treatment for the removal of sulfur-bearing materials such Vration, i-f desired.

E as ysulfate esters, which are formed together with alkylate in the reaction zone, although it is also within the scope of this invention to carry out this neutralization treatment immediately following the alkylation reaction and priorr to deisoparaftinization. The alkylate product which is .substantially free of .sulfur compounds is then treated forV further concentration and purification, for example, by subjecting the alkylate to deparafnization and fractional sepa- The process of the present invention is applicable to all alkylation processes involving the reaction between anisoparaffin and an olefin in the presence of acatalyst. The

isoparafiinswhich may be used include isobutane, isopentane, isohexane, etc., or mixtures thereof and the olefins reacted with these isoparafins include propylenes, butylenes, pentylenes, .and isomers and mixtures thereof. lt is within the `scope of this invention toutilize any proportion laV4 i' I also within the scope 4of this invention to introduce the of the above as feed stocks and, in addition, mixtures of isoparaffins and olefins in the presence or absence-Of n-parains. i

A wide variety of catalysts are available for use in Y the alkylation `of an isoparaiin (an alkylatable'hydr-ocarliquid catalysts Which provide a heterogeneous reaction mixture with the hydrocarbon may also be employed within the scope of .this invention.

- It is also to be understood that other types of condensationreactions, wherein avvapor-ous reactor efiiuent is pro-y duced, which is capable of supplying heat toa distillation Zone Aby reboiling .the liquid in the zone, are also within the scope of this invention. A particular example lof such a condensation reaction involves the alkylation of an aromatic compound such as benzene with an olefin such as propene. 1

The most preferred reaction of the present invention involves the reactionbetween isobutane and anulen in the presence of a sulfuric acid or hydrofluoric acid catalyst. enerally, the alkylation reactions take place over a wide range of .temperature and pressure', ranging from about -50 F. to Iabout 500 F. and from about 0 p.s.i.g. to about 1000 psig. AHowever, the preferred reaction of the present invention is preferably carried out at a temperatureof between about 25 F. and about y100" F. and a pressure .of .from about 5 p.s.i.g. to about 50'p.s.i.g.v

entire isoparafiin charge with the catalyst.

ln the operation of the present invention, the ratio of isoparaffin to acid is generally between about 2:1 and about 15:1 and the ratio of isoparaffin to olefin feed in a reaction zone falls withinv the Yrange'of from v'about 2A mols toabout 150 molsrof isoparatiin per mol of olefin.

Prior art Vprocesses have shown thatYmol ratios of about k10:1 or less isoparaiiin to olefin are commonly used; however, by the process of the present invention, as hereinafter described, mol ratios in the region of up to V200:1 arel obtainable and beneficial inthe production of high quality alkylate. It has been found that the formation of undesirable reaction products (esters) in the reaction zone is inversely-proportional tothe molar excess of i isoparaficm'while the formation of higherv quality alkylate is directly proportional to the molar excess ofL isoparaffin.

Therefore, mol ratios of between about 20:1 and about;

150:1 isoparain to olefin are preferred, The, higher mol ratios of this lrange are obtained when operating the deisoparatfinization zone as a stripper.

, Although the present alkylation process'is adaptable to any of the numerous types of contacting apparatus employed rfor alkylationand may be carried out inV one or more stages, the preferred apparatus and method which is particularly suited to the present process, is the casf cade type reactor wherein theV alkylatable hydrocarbon and acid are emulsified in each of'several confined reaction zones in'several stagespin series and the olefin is separately introduced and is uniformly dispersed throughout the emulsion inv each reaction zone. The reaction vmixture passes serially through the plurality of reaction zones within the reaction section of the contacter 'Wherein the temperature is maintained at a constant low levelV by vaporizing the lighter components of theV reaction mixture including some of the isoparain reactant. The

,reaction mixture then enters a separation section wherein liquid and vapor phases are separated; AkIn Vthe separation section, the liquid catalyst, preferably an inorganic acid such as sulfuric acid, is also removed from the liquid hydrocarbon phase and a portion of the acid separated is generally recycled to the reaction section, usually after being fortified with fresh acid soV as tol maintain kthe catalyst in a highly concentrated state, Vfor example, pref-V erably above about 85 percent sulfuric( acid.

In Vthe process of the presentV invention at least a portion of the liquid hydrocarbon phase which contains a mixture of isoparafiin, alkylate, acid esters and which However, the alkylation of an aromatic compound withV an yolefin is usually carried out at a temperature of from about 200 F. toV about 500CIV F.r To establish favorable conditions for theproduction of high octane alkylate in high yields, it is desirable to contact the reactants with vigorous agitation so `as to provide uniform mixture of the reactants and, to maintain atl the point of con-tact, a -high concentration of alkylatable hydrocarbon as compared to olefin. YThis can be accomplished by introducing' olefinic hydrocarbons into an emulsified stream Vof alkyla- [table hydrocarbons .and acid Which'is moving past the point ofv olefin introduction at a high or maximum velocity YWithin the reaction Zone. lThe majorportion ofthe isoparafin present in the reactor is kpreferably provided by `a recycle .stream obtained from a subsequent distillation v step namely, the deisoparainization step, and from the refrigerant stream as hereinafter described; although, a

i l major portion of isoparain may be continuously'supplied from anA outside source, if desired. Normally, a portion ofV the 4'isoparafiin is'introduced into the cont-actor with Ithe olefin Vreactant and ,a second portion is emulsified with Y' the Ycatalystprior toV Contact with olefin;` However, `it i5 k7,5

may or may not contain normal butane and residual acid catalyst, can be treated to remove traces of catalyst and ester contaminants, or can be passed to a deis'oparafnization zone wherein the isoparafhn is distilled fromthe ,alkylate mixtureV at a temperature between aboutY 50 F.

and about 260 F. under from about Ops-ig. to 100 `psig., preferablyat a tower bottoms temperature between about 50 F. and about 200 F. under a tower Vtop pressure from'about 0 p.s.i.`g. to about 60 p.s.i.g.

The ,deisoparafiinized alkylate can then be subjected to subsequent refinement steps such as, the removal of acid estersby water-washing, bauxite treating, caustic'washing or combinations of these or other known treating steps, deparafiinization and heavy alkylate.

Y The vaporousV hydrocarbons removed from theV con-` tactor as auto-refrigerant are compressed and passed in f indirectrh'eat exchange with theliquid material-in therA deisoparaffnization zone whereupon the. zione is reboiled and the auto-refrigerant isfat least Vpartially condensed,

the condensed portion being recycled to the` contacter as part of the isoparafhn feed thereto. The above treatment or refinement of the Vdecatalyzed liquid hydrocarbon effluent can ,beaccomplished byk various methods some of which are novel in the alkylation f art. For example, accordingV to the present invention,

Vvthe total liquid hydrocarbonefiiuent` can be treated for fractionation into light and` ester removal and then passed directly to a deparaftinization zone wherein normal paratiin and isoparaiiin are simultaneously removed from the aikylate by distillation. It may be that under certain conditions of low contaminant concentration, it is desirable to rst remove normal and isoparains and follow the depararlinization of the alkylate by treatment for the removal of esters according to one of the methods mentioned above. Nevertheless, according to the present invention, the removal of these impurities is more often carried out prior to removal of normd paraffin because of the high temperature required to free the alkylate of normal paratlin. At such a temperature the ester impurities decompose so that it substantial amounts of sulfur compounds are present, they will cause fouling in the distillation tower. However, when a catalyst other than sulfuric acid is employed in the alliyiation reaction, the liquid emuent may be free of these contaminants. During the deparatiinization in a first distillation zone, the resulting overhead mixture of normal paralin and isoparalin is withdrawn, and passed to a deisoparaihnization zone wherein isopararlin is separated as an overhead vapor from liquid normal paraffin in a second distillation zone.

Another method for treating the decatalyzed liquid hydrocarbon e'iuent involves passing the effluent to a fractionation zone wherein isoparaliin is removed as a vaporous overhead fraction, normal parailin is removed as a vaporous side fraction and deparanized alkylate is removed as a liquid bottoms fraction as a product or" the process. This product can be further fractionated into light and heavy product fractions if so desired.

When operating in this manner, however, temperatures attained in the lower portion of the fractionation zone are suicient to cause decomposition of sulfur-bearing contaminants which are usually present in the liquid hydrocarbon effluent when sulfuric acid is employed as the catalyst of the alkylation reaction. To avoid clogging in the fractionation zone, the total liquid downiiow in the fractionation zone is removed as a continuous stream of liquid hydrocarbon at a point between the normal paramn take-off and the bottom of the tower, treated for removal of contaminants and recycled to the fractionation zone, or the liquid eiluent is neutralized prior to fractionation.

The vaporous normal paralin stream is condensed and collected as a product of the process and the vaporous isoparaiiin fraction is subsequently condensed and recycled to the alkylation zone as a part of the feed thereto.

The most preferred embodiment for treating the liquid hydrocarbon etlluent in accordance with the present invention comprises passing the entire decatalyzed liquid hydrocarbon stream directly from the contactor to the deisoparafnization zone, deisoparahinizing the crude alkylate stream by distillation at about atmospheric pressure or a little above in a tower which is reboiled by indirect heat exchange with compressed, vaporous autorefrigerant, and the isoparatiin fraction thus produced, withdrawing the resulting deisoparaftinized alkylate from the rst distillation zone, washing or otherwise treating the crude alkylate for removal of impurities such as esters and acid, when they are present, then passing the deisoparainized alkylate stream to a second distillation zone wherein normal parain is separated from alkylate and withdrawing the liquid from the second distillation zone as the allrylate product of the process or passing the liquid to a third distillation zone wherein the alkyl-ate is separated into light and heavy fractions.

The lirst or the embodiments discussed above reduces the number of treating steps to which alkylate is subjected and since all no -allrylate material is substantially removed from the allrylate product in one step, a smaller volume of material is treated in the deisoparamnization zone and a more economical method of separating recycle isop-arain is realized.

The second embodiment, not only calls for the removal of substantially all non-allrylate material from the liquid product, but also provides for the immediate and continuous se aration of the various components present in the non-allrylate Vapor fraction. Thus, the second ernbodiment provides an additional economy in the operation of the above invention,

The third of the embodiments discussed above which involves the treatment of crude alkylate for removal of sulfur-containing impurities after the deisoparainization step, represents an advance over methods of the prior art, in that the washing or neutralization equipment, aside from being considerably reduced in size, operates to more .Frciently remove the sulfur compounds from the liquid phase containing allrylate wherein they are concentrated. A further advantage is that caustic cannot be recycled to the contactor and result in the consumption of acid, If such a procedure were followed in any of the alkylation processes known heretofore, the presence of sulfur compounds in the deisoparafinization zone would cause severe fouling in the iirst distillation tower due to the temperatures at which the tower is operated. lt is only by the conditions o the present invention, discussed above, and the process which provides means for operating under these conditions that the eiiiciency and economy of the present moded alkylation process is realized.

Although both of the novel methods of treating the liquid hydrocarbon stream discussed above nd application in the present invention, it is to be understood that the conventional arrangement of process steps, namely alkylation, treatment for the removal of sulfur compounds followed by deisoparahinization and the deparanization, is also within the scope of the present invention and also provides an advancement in the art in the thermodynamic etliciency of the present process.

rThe auto-refrigerant or vaporous hydrocarbon phase removed from the allrylation contactor, is treated to re- .iove any liquid entrained therewith such as, for example, liquid catalyst and the separated liquid is returned to the liquid hydrocarbon phase in the contactor while the vaporous material, which contains some of the isoparaiiin reactant and lower boiling hydrocarbons, is passed to a compressor and compressed to a pressure at which the condensation temperature will be sufficient to reboil the deisoparaiiinization tower and the vapors will be at least partially condensed by indirect heat exchange, i.e., all of the sensible heat down to the vaporization temperature and at least some of the heat of vaporization will be removed during the reboiling operation. In the case of the allrylation of isoparai'lin with butylene, the auto-refrigerant vapors are compressed, to between about 20 p.s.i.g. to about p.s.i.g. at a condensation temperature of between about 49 F. and about 140 F. and preferably when isobutane is the alkylatable hydrocarbon to between about 30 psig. and about 115 psig. at a temperature of between about 55 F. and about 130 F.

The compressed gas is removed from the compressor and is passed in indirect heat exchange with the material in the deisoparaffrnization zone, for example, by means of an external reboiler to supply heat and maintain distillation conditions in the deisoparai'iinization zone. One or more of such heat sources can be employed, if desired, by one or more vaporous streams leaving the compressor. In the practice of this invention, it has been found that part of the reboiling heat can be introduced above the bottom of the tower and that the higher the reboiler is placed on the deisoparatiinization tower, the lower the compression of vapor required for reboiling the tower. Therefore, if a plurality of reboilers-are employed to supply heat to the deisoparaiinization zone, the gaseous material employed as heat exchange media may be compressed as separate streams to various pressures, or it can be compressed as one stream and drawn ol at various pressure levels, in accordance with the requirement of the reboiler with which they exchange heat. It has alsoV been discovered that a reboiler which is in indirect heat suitable conditions exchange with compressed gaseous material can .be used in combination with another reboiler employing steam as a heat source or any other high temperatureV source of heat. For example, at least one lreboiler in indirect heat exchange with compressed gaseous material may be located at approximately the middle of the tower while may be directly recycled to the contractor at a suitable temperature and pressure for the alkylation reaction or partially condensed material may be further cooled to condense an additional amount of vapors and the resuling condensed portion returned to the contactor. lt is preferable to further cool the compressed material leaving the heat exchanger until at least a major portion, most preferably the entire portion, is present as liquid and then to flash the liquidthus produced to vaporize ma-V terials boiling below theV isoparafiin reactant and return the liquid isoparaihn portion to the contactor at a suitable temperature and pressure.V In this way, the lower boiling hydrocarbons are readily removed from the system as vapor and the vapor can be fractionated for separate recovery of the materials contained therein or otherwise treated in accordance with the requirements of the individual process. Thus, the isoparaiiin returning to the contactor is in a puriiied, more concentrated state, and the deleterious eifectsV of non-reactant materials in the feed, such as high circulation rates, high compression ref quirements, etc., is reduced to a minimum.

The deisoparaflinization tower can be operated at a lower, higher or they same pressure as that employed in the alkylation Zone. The vaporous isoparafn fraction is removed from the top ofthe deisoparafinization tower and the isoparaflin is passed to the compressor where these vapors become part of the heat exchange media and are mixed and compressed with the auto-refrigerant. inthe alkylation of isobutane with butylene, the isoparaiiin fraction, at a pressure between about p.s.i.g. and about 60 p.s.i.g. and between about F. to about 100 F., is compressed to between about p.s.i.g. and about 115 p.s.i.g. and to a condensation temperature between about Fyand about 130 F. The compressedgisoparahn vapor may be condensed and recycled to the contactor by means of cooling or cooling and flashing Vor it may be employed as a heat exchange medium to provide heat and maintain distillation conditions in the deisoparafnization zone in a separate reboiler. Preferably, the isoparafiin vapor is passed to the same reboiler as that to which the compressed auto-refrigerant from the contactor Y is passed since it is usually combined with auto-refrigerant in the compressor. lW'hen used as a heat exchange medium and after supplying heat to the distillation tower, v

either'separately or in admixture with the compressed auto-refrigerant, the compressed isoparaiiin overhead fraction, Vis cooled or cooled and flashed as hereinabove described and the resulting liquid portion recycled under pressure and at correspondingly low temperatures.

In commercial processes ofthe prior art, it has been necessary tooperate the deisobutanization zone at Vbottom to the contactor as a part of the feedy temperatures and tower top pressures in excess of 165 l?. and 100 p.s.i.g.,'which operation presents great heat exchange requirements Vfor which numerous expensive heat exchange units are provided betweenrthe contactor and the deisoparafnnization tower. ln addition to these diiiiculties, the processes of prior art have found it mandatory to perform the removal of sulfur compounds from the entire liquid phase leaving the contacter in a tedious and ineiiicient manneigprior to the deisoparaiiinization step where these compounds encounter conditions which cause their decomposition. The gum forming tendencies of sulfur compounds has been the source ofmuch expense attributed to shutting down and cleaning out the lines and trays of the deisoparafhnization tower and other subsequent distillation towers and, therefore, the utmost care lia-sheen exercised to remove small traces of` these con-Y taminants. By theprocess'of the present invention, these difficulties have been eliminated or reduced to a minimum by: (l) providing a thermodynamically more eiii-` cient alirylation process, (2) making'itV possible to operate the deisoparaiiinization zone at'conditions approximating those employed in the alltylation Zone thereby avoidingV decomposition of su fur compounds in this Zone and (3) providing an operation which can safely postpone'the treatment of crude allylate until after a large volume of the liquid Vhas been removed as, isoparafn, thereby reducing the lsizeof the equipment employed in the contaminant removal step. l n v When the deisoparaiiinization tower is operated as a stripper in the process ofV the present invention, the amount ofisoparaiin separated and available for recycle to the contactor is greatly increased, somthat mol ratios of isoparaiiin to olefin in the contacter may be increased from between about 2:1 and aboutV l0: 1 to between about 10:1 and about'200r1. Since the higher isoparaiin ratio in the contactor results in higher yields of better quality alkylate, and since the operation of the deisoparafiinzer tower as a stripper, or under conditions approaching a stripper, requires a smaller unit as compared with a reiiux tower, the deisoparafn stripper (or a tower with low reiiux) is preferred, although deisoparalinzation towers reference is now had Vto the accompanying drawings of which FGURE 1 is a diagrammatic illustration of an allylation process wherein a preterred'embodiment of the present invention is described. VEGURES 2, 3 and 4 Vare additional embodiments of alliylation y processes Y wherein applicants invention is employed.

Referring to FIGURE l Vwherein a Viirst embodiment exemplifying the invention in an allg/lation process is shown, isoparaiiin or the alltylatable hydrocarbon, is fed into contacter 3 from line 2 and is contacted witholeiin entering contacter 3 from lines 6, @(11), 6U?) and @(c).

, rEhe reaction is carried out under conditions hereinbeforeV described in the presence of catalyst, for example, sulfurie acid of at least percent concentration, entering the contacter from line 7. Generally, the alkylatable hyf drocarbon and the liquid catalyst are emulsified prior to ContactV with oleiinV thus increasing the rate of reaction and reducing the formation of undesirable lay-products toy a minimum. The isoparaiiin emulsionand olefin are re-V acted in the reaction Vsection 3(61) of the contacter, preferably by passing emulsion seriallyrtlnough a plurality ofreaction zones withseparate introduction of olefin into' each Zone.V During the reaction, a portion of the reaction mixture is vapor-ized in eachreaction zone and the vapors or auto-refrigerant is separately removed from each zone through lines l through 13(c) and returned to the con- ,tactor through line i301?) to provide cooling and, there-V fore, temperature control to the reaction section of the contactor. The resulting product mixture including the vapors returned through line 1Std), is then passed to a separation section .3(b) wherein a vaporous phase containing unreacted isoparairln and lower boiling hydrocarbons is separated from a liquid phase containing alkylate product, catalyst, lower boiling hydrocarbons and reaction by-products such as, for example, sulfate esters. Also in separation section 3(1)), the liquid catalyst is separated from the product mixture, withdrawn from the conductor by line 4 and a portion is recycled to the reaction section of the contactor through line '7 wherein it is mixed with fresh acid. The remaining portion of used acid is Withdrawn from the process in valved line 15 and may be regenerated for further use in the process. The `liquid product mixture is removed `from the contacter through line 8 and pumped to a deisoparanization tower 9, usually containing between about l and about 80 distillation trays. lf desired, a coalescer (not shown) can be inserted into line 8 to further separate the acid catalyst, and esters from the liquid product mixture, before introducing the mixture into tower 9.

The vaporous hydrocarbon phase or auto-refrigerant is removed from the separation section of the contactor through line vand is passed to a compressor 10 wherein the vapors are compressed to a pressure between about p.s.i.g. and about 125 psig., for example 50 psig. and a condensation temperature between about 49 F. and about 140 F., for example 75 F. Generally, a coalescer (not shown) is employed at the top of the contactor or in line S for separating liquid material entrained in the vapors and returning the liquid material to the liquid phase in separating section 3(b). Part of the compressed gases are then passed through line 12 into reboiler ld in indirect heat exchange with reboiler 14 for the deisoparaliinization tower 9 to supply heat thereto and to maintain distillation conditions in the tower.

soparaiiin is removed from the liquid product mixture through line 24 from the top of deisoparaiinization tower 9 as a vaporcus overhead fraction and is passed to compresser itl wherein it is compressed to a pressure of between about 20 p.s.i.g. and about 125 psig., for example, 50 psig. at a condensation temperature of between about 40 F. and about 140 F., for example 75 F.

Another compressed vaporous stream under between about 20 p.s.i.g. and about 125 p.s.i.g. at a condensation temperature of between about 40 F. and about 149 F. is removed from the compressor through line 26 and passed to cooler 23 wherein the vapors are condensed.

In a lirst embodiment of this process, valves i3 and 3S are in open position, valves 19, dil and 47 are closed and the compressor vapor material, which has been cooled to a liquid by the indirect heat exchange operation in heat exchanger 14, is recycled to the reaction section of the contactor through lines Ztl and Z, after passing through pressure reduction valve 2.2 wherein the pressure and the liquid is adjusted to the pressure employed in the alkylation reaction section 3(0). The condensed vapor from cooler Z8 is then transferred to holding drum Si?, from which a portion ot the liquid is Withdrawn by valved line 5S and passed to ashing zone 32. The remaining portion of the liquid in holding drum 3l), is passed through valved line 39 to a distillation zone (not shown) wherein hydrocarbons boiling below the isoparan reactant are withdrawn from the system as vapors and the resulting concentrated isoparaliin liquid is returned to the system in line 48 by means of valved line 35. The liquid material in zone 32 is flashed in indirect heat exchange with olefin entering the system through line 6 and the resulting vaporous materials are withdrawn from flashing zone 32 by means ot line 34 and recycled to compressor lo, while the resulting liquid portion is withdrawn from hashing zone 32 by line 36 and recycled to contacter' 3 through lines 20 and 2 after passing through pressure reduction valve 22.

The deisoparainized liquid product mixture is removed from the bottom ot deisoparatlinization tower 9 through line 5t? and passed to a neutralization Zone 52 wherein the liquid product is washed with caustic solution followed by a water-wash at an elevated temperature, for example, at about F. to remove traces of acid and sulfate esters from the product mixture prior to treatment at temperatures which cause decomposition of these impurities. The neutralized liquid product is then passed to deparainization tower 54 through line 56 wherein normal paratiin is distilled from the alkylate product at a bottoms temperature of between about 200 F. and about 360 F. under between about 4G p.s.i.g. and about 90 psig. The gaseous normal paraffin is withdrawn from the deparaiiinization zone, passed to cooler 7 to condense the vapor, passed to surge drum 59 and recycled to the top of the deparaiiinization tower as retlux thereto by means of line 5S. A portion of the retiuxing liquid normal paratiln is withdrawn from the process, through line 6i) while the liquid alkylate product is withdrawn from the bottom of deparal'linization tower 54 through line 62. It desired, the alkylate product can be further fractionated to separate light and heavy alkylate fractions in a rerun tower (not shown).

ln a second embodiment of the invention shown in FIGURE l, Valves 38, 47 and 19 are in closed position and valves i8, 39 and d@ are opened. The process is substantially the same as that described above in the lirst embodiment, except that concentrated isoparatlin is returned to the system by line 37 instead of line 35, and the liquid material in holding drum Sil is passed through valve 4d and line 64 and is joined with compressed gaseous material in line 12 as heat exchange media for heat exchanger 14 in indirect heat exchange with the liquid entering reboiler line l5. The cooled liquid material emerging from heat exchanger lll is then passed by means of line 12, valve t3 and line 2li to pressure reduction valve 22 to adjust the pressure of the recycle isoparain to correspond with conditions in the alkylation reaction zone and the recycle stream is thereafter introduced into contactor 3, together with fresh isoparaflin from line 2 as part of the isoparailin feed thereto. The subsequent treatment of the deisoparalinized liquid product mixture from tower 9 is substantially the same as described above.

In a third embodiment of the invention illustrated in FIGURE 1, valves 1S, 39 and 49 are in closed position and valves 38, 19 and 47 are opened. Here, as above, the process follows the description of the lirst embodiment, except that the total liquid material in holding drum 30 is passed through valve 38 and line 4d into flashing zone 3.?. wherein it is dashed by indirect heat exchange with olelin entering the system through line 6. The resulting liquid isoparain is passed to line 2li by line 36 from which, after proper pressure adjustment, it is recycled to the reaction section of contactor 3. The resulting vapors are passed through line 34 and a portion of this material is recycled to compressor liti through line 34 while the remaining portion is passed through line i2 to heat exchanger 44 in indirect heat exchange with the liquid product mixture in reboiler line ld of the deisoparaiinization zone. Thus, the alkylate product mixture or trap-out liquid in reboiler line 46 is heated and distillation conditions are maintained in the top of the deisoparalhnization tower. By the process of indirect heat exchange, the vapors are cooled to a liquid and are pumped :to a distillation zone (not shown) through line 42 wherein hydrocarbons boiling below the isoparaiiin reactant are removed from the system and concentrated liquid isoparaiiin reactant is returned to the process by means of valved line 35 which joins liquid material passing to the `Flashing zone in line 43.

The compressed vapor from compressor l@ is passed through line 12; into heat-exchanger 14 in indirect heat exchange with the liquid alkylate product mixture in reboiler line i6 as described in the rst embodiment. Howl1 ever, the material emerging from heat exchanger 1d in line 12, which has been cooled to a liquid, is passed into line 66 by means of valve 19 and this material enters flashing zone 32 by means of line d8. After flashing, theV liquid portion is recycled to contactor 3 by means of lines 3o, Ztl and 2 and valve 22, as previously described.

FIGURE 2 of the drawings illustrates an embodiment of an allrylation process wherein the liquid alkylate product mixturek is passed directly from the contactor to a neutralization zone and then to a deparallinization zone wherein isoparaiiin and normal paraffin are removed as found that contactors containing from 3 to 7 Vreaction zones are most preferred. The reaction of isoparaii'ln with oleiin takes place in the reaction section 74(a) of contactor 74 at a temperature of between about 25 F. and about 100 F. under between about 5 p.s.i.g. and about 50 p.s.i.g. After the reaction has taken place, the entire product mixture is passed to a separating section 74,(b) of contactor 74 wherein vaporous eliiuent or autorefrigerant is continuously separated from liquid product mixture containing acid catalyst, alkylate, unreacted isoparatiin, lower boiling hydrocarbons -and small amounts of sulfate ester impurities. The vaporous efuent is then withdrawn from the contactor in line 112 and compressed in compressor 1%. The acid catalyst is continuously separated from the liquid hydrocarbon phase, preferably by settling in the separating section 7t(b) and the separated acid is recycled to the reaction section of the con- -tactor through lines 7 8 and 72 wherein it is fortied with fresh acid from line 72 to maintain a high acid concentration. A portion of the used acid in line 73 can be withdrawn for regeneration through Valved line Si). The liquid product mixture is removed from the contactor by line 82V and is pumped into heat exchanger 86 in indirect heat exchange with parailins separated from the alkylate Vas hereinafter described. After being heated in heat exchanger 85, the liquid hydrocarbon product mixture ,isV

passed through line 84 and into a neutralization zone Se? wherein it is'contacted with bauxite for the removal of traces of acid catalyst and sulfate esters; although, caustic washing and/or water-washing may be substituted for theV bauxite treatment if so desired. The neutralized product mixture is removed from neutralization zone 38 and is passed to deparainization zone 9d by means of line d?. wherein the isoparan, normal paraffin and lower 12 paratlin overhead in line 1de is then passed to compressor 1116 wherein it is mixed with the vaporous reactor effluent and the vapors are compressed to two pressure levels, between about 20 psig. and about 125 psig. at a condensation temperature between about F. and about 140V F.V The normal paraffin is withdrawn from the system as a liquid bottoms fraction from deisoparallinization tower 1512 through line 1118. The distillation conditions in deisoparafinization tower 162 are maintained by indirect heat exchange of the material in the deisoparanization zone with compressed gaseous auto-refrigerant as hereinafter described.

The vapor or auto-refrigerant from contacter 74 is withdrawn through line 112 and passed to compressor 11i-5 wherein it is compressed to two pressure levels, between about 2G p.s.i.g.'and about 125 p.s.i.g., at a condensationV temperature of between about 40 F. and about 140 F. For example, one portion of the vaporous material in the compressor is pressured to'90 p.s.i.g. while the other portion is compressed to' 55'p.s.i.g. A portion of the compressed gases in compressor 1%, for-example, that portion whichY is under 55 psig., is removed through line Y the pressure is adjustedto that employed in the reaction section of the contactor, i.e., between about 5 p.s.i.g. to

about 5() p.s.i.g. and the liquid is recycled as part of the vcompressed material leaving the heat exchanger in line 122 is then passed to a cooler 128 wherein substantially all of the vapors not condensed in heat exchanger 12d, are liquiiied. TheV resulting condensed material is then accumulated in holding drum 13) and a portion passed Vto hashing zone 131i by means of line 132 while the re- Y maining portion iswithdrawn in line 131 for treatment 'in cooler 96 and pumped to holding drum A portion of the material removed from holding drum 9S is returned as reflux to deparainization tower .99 by line 9d and the remaining portion lis passed through'line 10i? VVinto heat exchanger 86 Vin indirect heat exchange with the liquid l product mixture from contactor 74. As a result of the yheat exchange step,` the hydrocarbon mixture in line 1% yisfurthe'r cooled and-,is then passed to .deisoparaitlnization towerj1d2, wherein isoparaffin y,and lower boiling Vhydrocarbonsare-removed'as an overhead'vapor in line 164,

Y from liquid vnor-mal paralinbyY distillation, fatV ka temperature betweenabout 20 F. and about 1005i?. 'under from about 15 psig. toA about 5.5 p.s.i.g. The' vaporousfisothe removal of low boiling hydrocarbons. ln liashingzone v134 the liquid material from holding drum 13d is ilashed and, by means of indirect heat exchange with olelins entering the system through line ,'7-5, cools said loleiins. The vapors which result from the Vflashing and heat ex- Vchange operation are removed through line 136 and rccycled to compressor 106, where they are compressed to pressures Vheretofore described. The remaining liquid portion is removed from the flashing zone through line 138 and passed to line 118 and then to pressure reduction valve 122 inV order to adjust the pressure of the recycle liquid to the requirements of the alkylation reaction zone;

Vtheliquid being recycled thereafter through lines 11d and itl to contactor 741-, together with isoparaflin in line 133 from the treatment Vfor removal ofk lowrboiling hydrocarbons, as part of the isoparaii'ln feed thereto.V

emulsion isfreactedwitholen from lines 142-14201) in reaction'sect'ion 144m) of a-cascade Valkylation reactor.- 144, Thefisoparathn enters the reaction section from line.

14d from` a Vsource hereinafter described, whileacid' is Y introduced through line 14S and emulsiiiedwith4 isoparafn Vpriorto contact with olefin` The reaction takesplace upon contact of oleiin kwith the vemulsionat a temperature of between`aboutn25 Fiand' about lOOF. unde'rfroniL about psig. to about 50 p.s.i.g. After the reaction is completed, the product mixture is transferred to a separating section 14403) within reactor 141twherein a vaporous eilluent or auto-refrigerant containing isoparaiin and lower boiling hydrocarbons, is separated from a liquid phase containing allrylate, acid catalyst, isoparaftin, normal parain and contaminants. Vaporization of the lower boiling components in each reaction zone during the alkylation reaction is effected as a temperature control and the total of these vaporized components comprise the auto-refrigerant removed from the liquid product mixture and thence from the reactor in line 166.

The liquid phase is separated, preferably by settling, into an acid catalyst phase and a liquid product mixture or hydrocarbon phase containing in addition to hydrocarbons, contaminants, such as, for example, sulfate ester by-products of the reaction and traces of acid catalyst. The acid phase is withdrawn from the reactor by line 150 and a portion recycled through line leid wherein it is fortilied with fresh acid to maintain a high acid concentration, preferably between about 85 percent to about 99 percent acid. A portion of the used acid is withdrawn from the system through valved line 152 and may be regenerated if desired.

The liquid product mixture is withdrawn from reactor 144i and transferred to deisoparatlinization tower 156 by means of line 154. Fresh isoparatlin required for the alxylation reaction to provide a mol ratio of between about 2:1 and about 150:1 isoparatlinzoleiin in the reaction zones is introduced into deisoparafnization tower 156 by line 153 from holding drum 160. The liquid product mixture is stripped of isoparailin reactant and lower boiling hydrocarbons in tower 15d at a bottom temperature of between about 50 P. and about 200 F. under tower top pressure from about 0 p.s.i.g. to about 60 psig.

The isoparain and lower boiling hydrocarbons are removed from tower 15d as a vaporous overhead fraction and are passed by line 16d to compressor 1d?. wherein they are compressed to two pressure levels ranging from pressures between about 20 p.s.i.g. and about 125 p.s.i.g. at condensation temperatures between about F. and about 140 F.

The vaporous auto-refrigerant is transferred by line 1de from reactor 144 to compressor l@ wherein the autorefrigerant is compressed to two pressure levels ranging from pressures between about 20 p.s.i.g. and about 125 p.s.i.g. at condensation temperatures from about 40 F. to about 140 F.

When the vapors passed to compressor 162 are cornpressed to different pressures and in accordance with the teaching of the invention the most highly compressed vapor is used to supply heat to a lower portion of the deisoparaidnization tower than the vapor compressed to a lower pressure. rDherefore, vapors compressed to between about 20 psig. and about 50 p.s.i.g. are removed from the compressor by line ld and passed to heat exchanger ld while the vapors compressed to between about 40 p.s.i.g. and about 125 p.s.i.g. are removed from the compressor by line 168 and used in heat exchanger 170. A portion of the vapors in line 16S is passed to heat exchanger 17d in indirect heat exchange with the liquid produc-t mixture in reboiler line i722 of tower 15d. The remaining portion of compressed vapors is passed to by-pass line ljdl into cooler 176, wherein substantially all of the vapor is condensed, and then into holding drum 17S from whence a portion of the liquid material is removed from the system through line 180 for further treatment in the removal of parafdns boiling below the isoparain reactant (not shown). The remaining portion 4of liquid from holding drum 73 is passed to line 1S?. and joins condensed heat exchange medium leaving heat exchanger 1.70 in line 16S. The condensed liquid, predominately isoparafdn reactant, is passed upwardly through line 132 to the compressed, vaporous heat exchange medium entering a more elevated heat exchanger Cil 18d from line 186 into indirect heat exchange with the liquid product mixture in reboiler line l of the deisopa-raliinization zone. This gaseous-liquid mixture supplies heat to the liquid product mixture and maintains distillation temperature in the deisoparaiiinization tower. The gas of the heat exchange medium is condensed by the heat exchange operation and resulting liquid is transferred to a pressure reduction valve T19@ by line 192 prior to entry into isoparatlin recycle line 146. By means of valve 190 the pressure of the liquid isoparafn is adjusted to a pressure suitable for alkylation.

The deisoparafiinized product mixture in tower 156 is removed as a liquid by line 19d and is pumped to heat exchanger 1% in indirect heat exchange with a reboiler line hereinafter described. The product mixture which is heated in heat exchanger 1% is then passed to a neutralization zone @d wherein it is washed with water at an elevated temperature between about F. and about F., and is then passed through a coalescer (not shown) to separate and remove the water before the product mixture is passed through line 1% into deparatnization tower 250. Normal parafn is separated from the allcylate product by distillation at a temperature between about 200 F. and about 350 F. under between about 40 p.s.i.g. and about 100 p.s.i.g. in tower 200. The norrnal parafin which is removed as an overhead vapor in line is cooled to a liquid in condenser 20d, passed to accumulator 20e and a portion returned to the top of tower Edil by line 202. The remaining portion of normal parailin leaving accumulator 2de is pumped out of the system in line 208.

Reboiler liquid is withdrawn from the bottom of tower by line 21d, pumped to heat exchanger 94 to supply heat to the product mixture entering the water wash 19S or pumped to valved heater by-pass line 212 which is provided for temperature control. The reboiler liquid from line 212 is combined with reboiler liquid from heater 194 in line 214i and the combined liquid is then passed from line .Z1- into heater 21.5 wherein the reboiler liquid is heated and partially vaporized at a temperature necessary to maintain the distillation temperature in tower 2.00 and then returned to tower 200 by line 2id.

The liquid alkylate product lin tower 200 is withdrawn as a product of the process lby line 21d or further separated into light and heavy alkylate by passing it from line 213 into an allrylate rerun tower or distillation zone (not shown) wherein light alkylate for example, aviation gasoline, is withdrawn from the top of the tower and heavy allrylate is withdrawn from the bottom of the rerun tower.

FEGURE 4 .illustrates another modification of the present invention wherein the alkylation reaction in contactor 220 .is substantially as described above in any of the preceding ligures. lsoparatlin enters the contacter from line 2.22 and is emulsitied with acid catalyst entering the contactor from line 2241-. The emulsion is then reacted with olefin which is separately introduced into each of a plurality of reaction Zones through lines 226, 226th), 225%), 225W) and 226W) in the reaction `section 225Mo) ot' contacter 220. After passing the emulsion serially through each of the reaction zones, removing the reaction vapors from each zone through lines 22d, 223m), Z'ZSUJ), tdc) and 22%(60 and returning the vapors lto the contactor through line 22%(6), the entire reaction mixture is passed to the separation section ZZQUJ) of contacter 220 wherein the vapors are passed through coalescer 230m separate liquid entrained therewith, the vapors being passed to line 232 while the separated liquid is returned to the liquid phase entering the separation section. ie combined liquid is passed through coalescer 234 to break the acid catalyst-liquid hydrocarbon emulsion. The liquid is then allowed to settler and acid catalyst is separated from the liquid hydrocarbon product mixture. Recycle line 235 is provided for removing the acid catalyst from the separa-tion section,

pumping it to line 2li whereinit ismixed with a suiiicient amount of fresh acid to maintain the concentra-` for emulsitication with isoparatlin. A portion of the spent acid is withdrawn from line 236 lthrough valved line 233,

Vpassed toV an additional se-ttler 2d@ in order .to recover and remove in line 242 any of the liquid product mixture entrained therewith. The spent acid is then sent to an acid recovery system (not shown) yfor concentrationwhile the separated liquid product mixture in line 242 is passe to deisoparatlinization tower 24:14.

The liquid alkylate product mixture separated in the contactor isvpumped through line 243 into coalescer 24E-o to further separate acid catalyst. The liquid product mixture is then withdrawn from coalescer 246 and pumped through line 25h Vinto deisoparaiiinization tower 244. In tower 244, vaporous isoparaliin and lower boiling hydrocarbons are stripped from the liquid product mixture at a tower top temperature of between about F. and about 160 F., under from about 0 p.s.i.g. to about 6() p.s.i.g. The vapors are removed overhead in line 254 and passed to a compressor 252 wherein they are compressed to a pressure of between about p.s.i.g. and abou-t 125 p.s.i.g. at a condensation temperature from about 50 F. to about140" P.

The vaporous eilluent or auto-refrigerant removed from the contactor in line 232 is passed to compressor 252 wherein they are compressed to ay pressure and temperature within the above-mentioned range.

Herein the process departs from the previously described embodiments. Valves 254 through 257' and 282i are opened and valves 25S through 261i are closed. A stream or" `compressed gas is withdrawn from compressor 252 in line 262 and a portion, necessary to maintain the temperature of distillation in tower 24d, is passed to heat exchanger 2&4 in indirect heat exchange with the trap-out liquid in reboiler line 2do to supply the necessary heat thereto. ln the heat exchangeV operation, the compressed gas is partially condensed and the partially condensed material is passed through line 263 wherein it is joined by the remaining portion of compressed gas which by-passes the heat exchanger in valved line 27?. The entire compressed gaseous-liquid heat exchange media is then passed to condenser 272 kwherein the entire mixture is cooled to a liquid. The resulting liquid is transferred to a rst `flashing zone 274i from which a liquid portion is removed through line 276 and passed to heatexchanger 27S through valved line 279. A portion ot the gas is removed from the iirst hashing zone 27d and passed to heat exchanger 27S through valved lines 281i and 3.5.5 for indirect heat exchange with the liquid portion previously mentioned fromzone 274 and the remaining portion of gas in line 2%, controlled by valve Zl, is passed on through line 28@ for return to compressor 252, wherein it is pressured to between about 2t) p.s'.i.g. and about 125 p.s.i.g.

The gas entering heat exchanger`2'` is condensed Vand transferred to holding drum 28d by line 2d?. while they liquid entering heat exchanger 275 from line 2791 is `flashed and partially vaporized; the vaporized portion n remaining liquid portionV in Yheat exchanger 27S is withdrawn by line 238 and split into two portions, one of which is passed to pressure reduction valve 2% and recycled to the reaction section of contacter 229 as part of aisance 'lo Y Y isoparathn reactant are removed from the'systcm by passing the combined liquid from holding drum Zl to adistillation zoneV (not shown) by means of line 292. ln this distillation zone, the lower boiling materialsare removed trorn thesystem as a vaporous overhead fraction while the isoparatn'reactant, which is removed as a liquid bottoms fraction is returned to the reactor by line 294. The advantage attained by this .arrangementV is Vthat smaller volumes of liquid are distilled for a given volume of lower boiling materials removed from the system. Therefore, a smaller more efficient distillation Zone can be employed in this embodiment of the present process. The total portion of liquid in drum 2% is withdrawn by line 292 and is pumped toa distillation zone (not shown) for removal of hydrocarbons boiling below the -isoparafiin reactant, after which, the concentrated isoparaftin reactant is returned tothe recycle stream by v means of'line 294.

The liquid alkylate product mixture is withdrawn from the deis'oparafnization tower 244 by line 2%, passed to a neutralization zone 29S wherein sulfate esters and other impurities are removed in accordance with teachings described above. The product mixture is then passed to deparaliinization zone 34B@ from line 362 wherein the allrylate is separated from normal paraffin Yat a tempera` ture of between 4about 260 F. and about 360 F. under from about p.s.i.g. to about 10G p`.s.i.g. The normal ,parain is removed from zone '36d as an overhead vapor stream, a portion of which `serves as redux tothe tower, and the liquid alkylate product is withdrawn therefrom by liney 39:4 and passed to rerun tower 3th? operating at a bottoms temperature of between about 250 F. and about 450 F. under tower top pressure from 0 p.s.i.g. to 20 p.s.i.g. A light alkylate fraction islremoved from tower 3% as an overhead vapor, condensed in reflux line SGS by means of condenser 3l@ and a portion of the resulting Vliquid removed as a product of the process; the remaining portion serving as reflux to the tower. A heavy liquid alkylate fraction is removed from the bottom of tower 3% in line 312 as the heavy alkylate product of this process. f Y

Vln'a second modification of the process ot this invention the process steps, including the alkylationA reaction, deisoparaftinization, compression and indirect heat exchange in heat exchanger 264!- are exactly the same as those previously described in FlGURE 4. This process departs from the previous process in that valves 25o, 257 and`255 are closed while valves 25S, 259, ,26u and 261 are opened and the vapor from flashing zone 274 in place of being passed in indirect heat exchange with the liquid portion from 27d, is passed in indirect heat exchange in hashing zone 27? with trap-out liquid in lines 324 and 325 from tower 24dto supply heat thereto `and to maintain the distillation temperature in tower 24d. The vapor from flashing zone 2"/'4` is passed through valved line 31.6 into heat exchanger 27S where part or'all ofit condenses. The vapor portion flows through lines 28d vand 2S@ for Y compression in compressor 252, while a portion of the the isoparatlin feed thereto through line 222 and the sec- Y ond of which is withdrawn from line 283 by valved line 289 and passed to holding drum 234. Y Y, v

' The combined liquid `in hol-ding drum 28d has a higher concentration of low boiling materials than eitherV the lauto-retri'gerant stream or the ydeisoparatlinizqation tower overhead by reason of the tlashing and separating operation in zone 274i. The'materials boiling below the liquid is recycled to contactor 22h through line 2% and the remaining portion is passed to holding drum2aY by means ot-valvecl'line'ZtiQ.V The liquid portion from the Iirst flashing zone '274 passes through valved lines 276 and 33th and into line 238 for recycle to the reaction section of contactor 220. The remaining steps of the process, namely the treatment of the deisoparaiiinized alkylate, including neutralization, deparatiinization, and distillation to separate light and heavy-alkylatefractions, are

y substantially the same as Vthose described above for FIG- The .following examples areoffered as a'rbvetterV understanding of the present inventiongandrare notto .be con-V strued as unnecessarily limiting to the scope thereof. The examples are carried out according to the teachings of the speciiicationand the drawings described above.

1 7 Example 1 Into a cascade alkyl-ation reactor is fed a continuous stream of isobutane containing about percent nor-mal butano and sulfuric acid of about 98 percent concentration in a mol ratio of about 7:1. The isobutane and sulfuric acid catalyst are emulsified and passed to a confined reaction Zone Where-in the emulsion is contacted with butylene in a mol ratio of about :1 isobutanezbutylene. The reaction between the isobutane and butylene to -forrn octanes takes place at F. under .about l1 psig. in a plurality of confined reaction Zones through which the emulsion is passed serially while contacting butylene introduced separately into each zone. The resulting reac- .tion product mixture is then passed to .a separating zone wherein vapors formed during the reaction, comprising isobutane, and lower boiling hydrocarbons such as propane are separated from a liquid phase containing isobutane, n-butane, alkylate product, sulfuric acid and small amounts of butyl sulfatos. The liquid phase passed through a wire mesh screen and is allowed to settle for .about 10 minut-es after which the acid which separates from the hydrocarbon liquids is withdrawn and recycled to the reaction zone.

The hydrocarbon liquids or alkylate product ymixture is Withdrawn Ifrom the reactor at a temperature of about F. -under about 8 p.s.i.g. and is passed through a coalescer to further separate entrained acid and sulfurbearing impurities therefrom. The liquid product mixture is then transferred to a deisobutanization tower wherein the liquid is stripped o-f isobutane and lower boiling hydrocarbons such as propane. The vaporous material is withdrawn from the reac-tor at a temperature of about 45 F. under about 8 p.S.i.-g. and passed to a coalescer wherein entrained liquid is separated therefrom. The vapors are then transferred to a compressor from which two compressed vaporous streams are withdrawn; one at 47 p.s.i.g. and the other at 80 p.s.i.g. The compressed vaporous stream under 47 psig. is passed in indirect heat exchange with the liquid material in the deiso- Ibutanization tower to supply heat thereto and to maintain the distillation temperature within the stripping tower. For example, the compressed gas at a condensation temperature of 65 F. is passed in indirect heat exchange with liquid material leaving the deisobutanization tower in a reboiler line at about 53 F. and returning liquid material to the deisobutanization tower at 58 F. The top of the deisobutanization tower is maintained ata pressure of about 16 p.s.i.g. and about 26 F. while the bottom of the tower is maintained under about 21 psig. and about 84 F. Vaporous isobutane and lower boiling components are removed from the top of the deisobutanization tower at about 26 F. and passed to the compressor. The heat exchange media which has been condensed by heat exch-ange with the liquid product mixture in the deisobutanization zone is then passed to a pressure reduction valve wherein the pressure is reduced from 47 p.s.i.g. to about 26 p.s.i.g. and the resulting liquid is ythen recycled to the alkylation reaction z-one for further contact with butylene. `Part of the vaporous stream which has been compressed to 8O p.s.i.g. at a temperature of 120 F. is passed to a condenser wherein the temperature is lowered to 100 F. for the total liquiiication of the vapors while another portion is passed in indirect heat exchange with a trap-out liquid entering bott-om reboiler at 65 F. and returning to the tower as a lquid vapor mixt-ure at 89 F. The resulting liquid streams from the bottom reboiler and condenser are then mixed with the heat exchange media prior to heat exchange in the upper reboiler.

The deisoparafiinized liquid product mixture is removed from the bottom of the deisobutanization tower at a temperature of .about 84 F. and is washed with water at a temperature of about 140 F. for removal 'of traces of sulfur-bearing contaminants. The wash water is disi8 carded as the liquid product mixture passes through a coalescer and the hydrocarbon lis then transferred to a debutaniZati-on zone wherein, at .a bottom temperature lof about 330 F., under 80 p.s.i.g., normal butane is separated from the alkylate product. This alkylate product is then further vfractionated in a rerun tower to obtain a fraction of aviation gasoline and a higher boiling fraction comprising heavy alkylate.

The invention as described herein relates to an improved method for reboiling a distillation tower. rThis method comprises reacting hydrocarbons under such oonditions that a vaporous efiuent and a liquid product etiiuent are produced, passing the liquid effluent to a distillation Zone to remove one of the liquid components boiling below said product, compressing the vaporous etiiuen-t to one or more pressure levels and passing the compressed vapors Iin indirect heat exchange with said zone, the vapors lbeing compressed to la pressure at which the temperature of the vaporous eifiuent is above the boiling .point of the boiling point of the component to be removed, below Ithe boiling point of the reaction prod-uct .and lthat at which at least part 4of the vapors are i condensed during the heat exchange operation.

When the vaporous eiuent conta-ins a rea-ctant of the reaction, the reactant is generally recovered, condensed and recycled to the .reaction Zone. When the lower boiling component removed from the distillation zone as a vapor also contains reactant, this vapor can be combined with the vaporous leffluent and the combined vapors compressed and passed in indirect heat exchange with the distillation tower to reboil said tower. Although the above described improvement relates particularly to alkylation reactions, it is t-o be understood that other types of reactions, wherein a vaporous eiiiuent is produced and .a liquid product eiiiuent is produced for subsequent distillation, are also within the scope of this invention.

The .method for .rebo-iling the deisoparaiiinization tower can be any of the procedures herein describe-d, and numerous modifications and altera-tions of these procedures will become apparent to those skilled in the art without departing from the scope of this invent-ion.

Having thus described my invention I claim:

ll. in an alkylation process which comprises contacting isobutane with an olefin in the presence of sulfuric acid in an alkylation contacter to produce a vaporous hydrocarbon etiiuent containing isobutane and a liquid eiiluent containing sulfuric acid, alkylate and unreacted isobutane; separating the vaporous efduent from the liquid eiiiuent; separately removing sulfuric acid from the liquid cfiiuent; and subjecting the resulting liquid alkylate mixture to deisobutanization; the improvement which cornprises: passing the liquid alkylate mixture to a deisobutanzation zone; removing isobutane as a vaporous fraction from said zone; compressing the vaporous fraction and the vaporous eiiiuent to the pressure levels Within the range of between about 20 p.s.i.g. and about 125 p.s.i.g. at a condensation temperature of between about 40 F. and about 140 F.; maintaining as two distinct and separate streams the vapors compressed to different pressure levels supplying heat necessary to effect the aforementioned deisobutanization of said liquid alkylate mixture in said zone by passing the vapor compressed to the lower pressure in indirect heat exchange with the deisobutanization zone in a iirst heat exchanger to reboil said zone, and passing the vapor compressed to the higher pressure in indirect heat exchange with the deisobutanization zone at a point below said iirst heat exchanger to reboil said zone in a second heat exchanger; condensing the low pressure vapor in said first heat exchange operation; recycling the resulting liquid to the alkylation contactor as part of the isobutane feed thereto; condensing the higher pressure vapor and flashing the resulting condensate in a third heat exchanger to produce a vaporous phase and a liquid phase; recycling the vaporous phase to said compression step; recycling the l3. The processV of claim 1 wherein the liquid in the de- I lisobutanization zone is further reboiled 'by indirect heat exchange of the liquid alkylate mixture with the Vmate-v rial in the third heat exchanger.

' 4. In an alkylation process Vwhich comprises contacting an oleinrwith an isoparain inthe presence Vof sulfuric acid as a catalyst in an alkylation contactor to produceV a vaporous hydrocarbon efuent containing unreacted isoparafn and a liquid effluent containing catalyst, alkylate, normal parain and .unreacted isoparafn; separating the vaporous effluent from the liquid effluent; separately removing the catalyst from the liquid effluent; and subjecting the remaining liquid alkylate mixture to deparainization; the improvement which comprises:

passing the liquid alkylate mixture to a deparai'linization Zone and withdrawing unreacted isoparaffln as a vaporous overheadfraction, normal paraffin as a vaporous middle fraction and liquid alyklate as aliquid bottom fraction from said deparainization'zone; recovering `alkylate fromrthe bottomfraction as a product of the-process; compressing a mixtureV of the vaporous overhead fraction and the vaporous eiluent to al plurality of different pres- Y sure levels; maintaining as distinct and separate streams each of the vapors compressed to a different pressure; reboiling the upper portion of said zone from which the vaporous overhead fraction is removed by passing the vapor compressed to the lowest pressure level in indirect heat exchange with the liquid in said upper portion of said deparaffinization zone; passing vapor compressed to an intermediate pressure level in indirect jheat exchange with` the liquid in the middle portion of said zone from which normal paran is removed to reboil said middle portion of said deparafnation zone; passing the vaporV 5. In `alkylation process which comprises contacting i anV olefin with an isoparain'in the presence of sulfuric acid as a catalyst in an alkylation contactor to produce a vaporous hydrocarbon eluent containing unreacted isoparan and a liquid elluent containing catalyst, alkylate,

' of the deparainization zone; and condensing compressed vapors in each of the heat exchange operations.

normal parain and unreacted isoparaiin; separating the vaporous effluent from the liquideflluent; separately removing the 'catalystfrom the'liquid effluent; and sub- Vjectin'gfthe remaining liquid alkyl'ate Vmixture to deisoparainization; the improvement which comprises: passing the liquidalkylate mixturetoa deparaflinization zone which is operated as a strippersubstantially without reflux; withdrawing unreacted'isoparaflin as a vaporous overhead fraction from said zone; withdrawing normal paraffin as a vaporous side fraction from said zone; condensing said normal Y.paraffin Vand recovering the condensate as a product of the process; continuously withdrawing a liquid alkylate stream'from the lower portion of p said zone; treating the liquidV alkylate stream for the neu`V tralization and removal "of contaminants; continuously recycling thegdecontaminated Vliquid alkylate stream to thev lower portion of said stripping zone; *removingl deparainizedfliquid alkylate from the bottom of said zone asV a product of the process; compressing the vaporous overhead fraction and the vaporous eilluentto a plurality of pressure levels varying between about 2() p.s.i.g. and about p.s.i.g. and passing Vthe gaseous stream of each pressure level as an'indirect heat exchange-Vmedium to a separate heat exchange with liquid' from the deisobutanization zone to reboil said-zoneV at each-site of heat exchange and to condense the compressed vapor in the heat exchange operation; passing the condensed vapor to a ashing zone; passing the liquid portion fromV said flashing zone to a separate heat exchanger; withdrawing and recycling the liquid from said separate heat exchanger to the alkylation-feontactor as part of the isoparaflin feed thereto; Vret-urnin'gthe vaporous portion from said separate heat Aexchanger and a portion of the vapors from said flashing zone to said compressor; condensing the remaining portion of vapors from said irst ilashing zone by indirectv heat exchange with the liquid from said ila'sln'ng zone in said separate heat exchanger and passing said ALPHoNso D. SULLIVAN, Primary Examiner. ALLAN M. BonrrcHnR, Examiner. 

1. IN AN ALKYLATION PROCESS WHICH COMRISES CONTACTING ISOBUTANE WITH AN OLEFIN IN THE PRESENCE OF SULFURIC ACID IN AN ALKYLATION CONTACTOR TO PRODUCE A VAPOROUS HYDROCARBON EFFLUENT CONTAINING ISOBUTANE AND A LIQUID EFFLUENT CONTAINING SULFURIC ACID, ALKYLATE AND UNREACTED ISOBUTANE; SEPARATING THE VAPOROUS EFFLUENT FROM THE LIQUID EFFLUENT; SEPARATELY REMOVING SULFURIC ACID FROM THE LIQUID EFFLUENT; AND SUBJECTING THE RESULTING LIQUID ALKYATE MIXTURE TO DEISOBUTANIZATION; THE IMPROVEMENT WHICH COMPRISES: PASSING THE LIQUID ALKYLATE MIXTURE TO A DEISOBUTANIZATION ZONE; REMOVING ISOBUTANE AS A VAPOROUS FRACTION FROM SAID ZONE; COMPRESSING THE VAPOROUS FRACTION AND THE VAPOROUS EFFLUENT TO THE PRESSURE LEVELS WITHIN THE RANGE OF BETWEEN ABOUT 20 P.S.I.G. AND ABOUT 125 P.S.I.G. AT A CONDENSATION TEMPERATURE OF BETWEEN ABOUT 40*F. AND ABOUT 140*F.; MAINTAINING AS TWO DISTINCT AND SEPARATE STREAMS THE VAPORS COMPRESSED TO DIFFERENT PRESSURE LEVELS SUPPLYING HEAT NECESSARY TO EFFECT THE AFOREMENTIONED DEISOBUTANIZATION OF SAID LIQUID ALKYLATE MIXTURE IN SAID ZONE BY PASSING THE VAPOR COMPRESSED TO THE LOWER PRESSURE IN INDIRECT HEAT EXCHANGE WITH THE DEISOBUTANIZATION ZONE IN A FIRST HEAT EXCHANGER TO REBOIL SAID ZONE, AND PASSING THE VAPOR COMPRESSED TO THE HIGHER PRESSURE IN INDIRECT HEAT EXCHANGE WITH THE DEISOBUTANIZATION ZONE AT A POINT BELOW SAID FIRST HEAT EXCHANGER TO REBOIL SAID ZONE IN A SECOND HEAT EXCHANGER CONDENSING THE LOW PRESSURE VAPOR IN SAID FIRST HEAT EXCHANGE OPERATION; RECYCLING THE RESULTING LIQUID TO THE ALKYLATION CONTACTOR AS PART OF THE ISOBUTANE FEED THERETO; CONDENSING THE HIGHER PRESSURE VAPOR AND FLASHING THE RESULTING CONDENSE IN A THIRD HEAT EXCHANGER TO PRODUCE A VAPOROUS PHASE AND A LIQUID PHASE; RECYCLING THE VAPOROUS PHASE TO SAID COMPRESSION STEP; RECYCLING THE LIQUID PHASE TO THE ALKYLATION CONTACTOR AS PART OF THE ISOBUTANE FEED THERETO AND RECOVERING A DEISOBUTANIZED ALKYLATE MIXTURE FROM THE DEISOBUTANIZATION ZONE. 